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[PATCH v3 01/17] gcc PR 88409: miscompilation due to missing cc clobber in longlong.h macros
- From: Vineet Gupta <Vineet dot Gupta1 at synopsys dot com>
- To: libc-alpha at sourceware dot org
- Cc: linux-snps-arc at lists dot infradead dot org, Vineet Gupta <Vineet dot Gupta1 at synopsys dot com>
- Date: Fri, 6 Mar 2020 10:24:03 -0800
- Subject: [PATCH v3 01/17] gcc PR 88409: miscompilation due to missing cc clobber in longlong.h macros
- References: <20200306182419.13945-1-vgupta@synopsys.com>
simple test such as below was failing.
| void main(int argc, char *argv[])
| {
| size_t total_time = 115424; // expected 115.424
| double secs = (double)total_time/(double)1000;
| printf("%s %d %lf\n", "secs", total_time, secs); // prints 113.504
| printf("%d\n", (size_t)secs);
| }
The printf eventually called into glibc stdlib/divrem.c:__mpn_divrem()
which uses the __arc__ specific inline asm macros from longlong.h which
were causing miscompilation.
include/
2019-03-28 Vineet Gupta <vgupta@synopsys.com>
PR 89877
* longlong.h [__arc__] (add_ssaaaa): Add cc clobber
(sub_ddmmss): Likewise.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
stdlib/longlong.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/stdlib/longlong.h b/stdlib/longlong.h
index ee4aac1bb5a0..638b7894d48c 100644
--- a/stdlib/longlong.h
+++ b/stdlib/longlong.h
@@ -199,7 +199,8 @@ extern UDItype __udiv_qrnnd (UDItype *, UDItype, UDItype, UDItype);
: "%r" ((USItype) (ah)), \
"rICal" ((USItype) (bh)), \
"%r" ((USItype) (al)), \
- "rICal" ((USItype) (bl)))
+ "rICal" ((USItype) (bl)) \
+ : "cc")
#define sub_ddmmss(sh, sl, ah, al, bh, bl) \
__asm__ ("sub.f %1, %4, %5\n\tsbc %0, %2, %3" \
: "=r" ((USItype) (sh)), \
@@ -207,7 +208,8 @@ extern UDItype __udiv_qrnnd (UDItype *, UDItype, UDItype, UDItype);
: "r" ((USItype) (ah)), \
"rICal" ((USItype) (bh)), \
"r" ((USItype) (al)), \
- "rICal" ((USItype) (bl)))
+ "rICal" ((USItype) (bl)) \
+ : "cc")
#define __umulsidi3(u,v) ((UDItype)(USItype)u*(USItype)v)
#ifdef __ARC_NORM__
--
2.20.1